The portion of the data communication field that is concerned with establishing a data link with a mobile transceiver is generally concerned with either wireless data links or cellular data links. Additionally, simulcast systems have been utilized to establish for such data links, as disclosed in U.S. Pat. No. 4,968,966, issued Nov. 6, 1990, and U.S. Pat. No. 4,918,437, issued Apr. 17, 1990. Additionally, another system that has been utilized to allow data transfer to a non-stationary location is the CT2 systems. A yet further system for transmitting data to a non-stationary location is disclosed in U.S. Pat. application Ser. No. 661,078, entitled "Adaptive Cellular Paging System", filed Feb. 25, 1991.
In cellular communication systems, the non-stationary transceiver is allowed to roam among a plurality of transmitter locations. The transceiver in the non-stationary location is tuneable to one of a plurality of frequencies such that when the transmission is weak in one transmission location or "cell", the transceiver can establish communication with a transmitter in another cell and "hand off" the communication. This type of system is typically utilized for voice communication, but digital FAX communications can be effected over these data links. In the cellular communication system, the non-stationary transceiver is always in communication with one of the cells. As soon as the transceiver at the non-stationary location is turned on, it establishes a connection with adjacent ones of the transmitters in adjacent ones of the cells on one or more separate control channels. When data is to be transferred to the non-stationary transceiver, the overall system determines which transmitter is to be the RF link closest to the non-stationary transceiver and then instructs the non-stationary transceiver to tune to a receiving channel and a transmitting channel and then the data link is effected. These systems tend to be rather complex.
In another type of system, that disclosed in U.S. Pat. No. 4,968,966, a plurality of cells are defined, each with a paging transmitter associated therewith. Each of the paging transmitters associated with the cells is operable to receive a simulcast transmission in the form of a location request have an address associated with a particular non-stationary location. This non-stationary location is typically in the form of a paging receiver. The paging transmitters then transmit this information out at the same time and the paging receiver will receive the information from the one of the paging transmitters having the strongest signal. The paging transmitter then acknowledges the receipt of this request by transmitting back to the paging transmitters and an associated receiver an acknowledgement signal. Thereafter, data can be transmitted to the paging transmitter that received the acknowledgement signal for retransmission to the paging receiver. Of course, this is typically a one-way transmission.
In the CT2 system, various base stations are disposed around a given location, each base station having the ability to establish and maintain a communication link with a portable transceiver. The base station is connected through the public telephone network to a master station. Typically, the base station can independently validate whether a call coming from a remote transceiver is acceptable as a subscriber, and then establish a telephone link over the public telephone network. However, one disadvantage to this type of system is that it is difficult to call a remote transceiver, as location of the remote transceiver is not known relative to the location of the base stations.